Tangram is one of the best known puzzles in the world, and went through at least two fads: one in the early nineteenth century, and once more when American puzzlist Sam Loydd published a booklet about it. The oldest known tangram dates back to about 1800.
In 1742, a little book about a Japanese seven-piece puzzle was published under the pseudonym Ganreiken. The real name of the author is unknown. The title was “Sei Shonagon Chie-no-ita”, or the ingenious pieces of Sei Shonagon. Sei Shonagon was a court lady who lived approximately 966 – 1017. There is no clear reason why Ganreiken named his 32 page booklet after her. The booklet has 42 patterns with answers, but the shapes are inaccurate. A copy of the booklet has been distributed at one of the International Puzzle Parties, but as I’m not in contact with anyone in higher puzzle circles I don’t have access to it. A year later Ganreiken published another book with more exercises. In about 1780, Takahiro Nakada wrote a manuscript entitled “Narabemono 110 (110 Patterns of an Arrangement Pattern),” and Edo Chie-kata (Ingenious Patterns in Edo) was published in 1837. Alas I was unable to find these figures on the internet.
There are surprisingly few publications in the west about this puzzle. Jerry Slocum devotes half a page of it in his book “The history of Chinese Tangram”, and Jerry Slocumn and Jack Botermans describe it in their “Zelf puzzels maken en oplossen”.
The Sei Shonagon consists of 7 pieces, like Chinese Tangram, which make up a square. Unlike Tangram, they can be fitted together to make up a square in two different ways.
I will leave the other square as an exercise for you.
They can also form a square with a whole in the middle:
The figure with the hole in the middle is one of the original puzzles.
Where the Chinese tangram has 13 convex shapes, Philip Moutou showed that Chie no-ita has 16 possible convex shapes. In geometry, a shape is called convex if any two points of the figure can be connected by a straight line which is entirely within the figure. I intend to publish about them in a subsequent post.
Presented here are 28 of the original problems.
You can check your solutions here
A new puzzle is published every Friday. Solutions are published after one or more weeks. You are welcome to discuss the puzzles, their difficulty level, originality and much more.
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